MSVC x64 support

[zyluo]

Hashes implented in MASM inspired by Project Nayuki Requires Build Tools for Visual Studio to cargo build https://visualstudio.microsoft.com/thank-you-downloading-visual-studio/?sku=BuildTools&rel=17

Fixex #17

[zyluo]

Please advise how to add MASM tests in the current github-actions

[tarcieri]

Per this note in the toplevel README.md:

https://github.com/RustCrypto/asm-hashes#note-this-repo-is-in-maintenance-mode-only

...the way we'd prefer to support all platforms going forward is by using the newly stabilized inline asm! feature

[zyluo]

understood. Thanks.